Method of producing cheese and product thereof

ABSTRACT

A method of cheese production using ultrafiltrated, concentrated milk, to which is optionally added a further retentate made from ultrafiltrated milk which has been acidified with at least one starter culture to obtain a pH value of from 4.5 to 5.6. Salt and other additives are added and while supplying cheese rennet, the retentate is pumped into cheese molds or ready-made packages in which the cheese receives a final heat treatment at from 18° to 65° C. for a period of from 4 to 36 hours.

FIELD OF THE INVENTION

The present invention relates to a method of producing cheese on thebasis of ultrafiltration-concentrated milk and cheese produced by themethod.

A commonly used method of cheese production on the basis ofultrafiltration-concentrated milk includes in the addition of starterculture to obtain a pH-value of about 6 followed by addition of rennet,preferably chymosin, whereupon the cheese milk still in its fluid stateis dosed into molds or directly into tins. After coagulation and finalacidification, salt in its dry state is added. Depending on the size ofthe cheese, an acceptable salt distribution is obtained within aboutnine days and nights, but the salt diffusion may take up to 42 days andnights,

In the method described in AU-B-32175/84 concentrated cheese milk isadmixed with usual additives, including sodium chloride and rennet, andacidogene in the form of glucono-delta-lacton (GDL), which graduallyacidify the milk by cleaving off hydrolytically glyconic acid, followingwhich the cheese milk, still in its fluid state, is dosed intoindividual packages. Renneting, acidification and coagulation areeffected after a few hours in the packaging. In this method 3.5% ofnon-milk additives in the form of GDL or other non-bacterial acidogenesare used. The chemical non-bacterial acidification of the cheeseprovides no ripening, i.e. no development of flavors, with enzymes fromstarter culture. Here the ripening is dictated solely by rennet enzymeand fat decomposition, the latter being intensified by homogenization ofthe cheese milk both prior to and following concentration.

U.S. Pat. No. 4,268,528 discloses a method of the production of cheesewherein a mixture of a whole-milk ultrafiltration-retentate and anultrafiltration-retentate of a lactic acid-fermented milk having apH-value ≦4.4 is cooled to between 0 and 4° C. during stirring toresuspend flocculated casein, is heated to above 4° C. and rennet isadded following which the casein coagulates. Acidification of the milkprior to the ultrafiltration results in more calcium being filtered offas the amount of dissolved calcium is higher at a low pH-value.Acidification of milk to a pH-value of about 4.6, which is theisoelectrical point of the casein, usually effects flocculation whichimpairs a subsequent rennet coagulation. In the method described theflocculated casein is resuspended and normal rennet coagulation isobtained.

In a normal continuous cheese production where the still fluid cheesecurd is poured into ready-made packages which are sealed hermetically ithas not been possible so far to vary the flavor and texture of thefinished cheese after the filling and sealing of the package.

Furthermore it has not been possible to continuously produce cheese withtaste character coming from impure or uncharacterized bacteria cultures,such as bacteria from non-pasteurized milk or whey from the previousday's cheese production as it is practiced in conventional cheeseproduction as such cultures may have undesirable properties such asoverdevelopment of taste and air formation.

It is the object of the invention to be able to produce cheese on thebasis of acidified ultrafiltration-concentrated milk (retentate) in acontinuous method at a uniform temperature wherein renneting andcoagulation are effected after the filling into the ready-made packages,where differentiated heat treatment may be used to obtain differentiatedproducts and where the desired salt concentration and distribution areobtained immediately.

It is a further object of the invention to produce cheese withaccelerated ripening and increased opportunity for taste control byadding at least one type of ripened curd to the acidified retentatewherein the milk components may optionally be adjusted or by adding ataste concentrate made by the fermentation of permeate enriched withmilk protein and optionally milk fat.

It is a further object of the invention to be able to produce cheesewith a taste character deriving from impure bacteria cultures with knowntaste character, e.g. bacteria from non-pasteurized milk, from localcheese specialties or whey from the previous day's cheese production,without such impure bacteria cultures being transferred to the cheeseand causing development of air.

It is furthermore an object of the invention to be able to vary taste,texture, etc., during the cheese production by use of several differentstarter cultures. A mixture of starter cultures in the sameacidification tank is undesirable as it usually results in only oneculture proliferating in the cheese milk, seeing that the pH optimum,temperature optimum, etc., differ for the different cultures.

It is a further object of the invention to obtain a simplification ofthe production methods by continuous production of cheese in ready-madepackages.

SUMMARY OF THE INVENTION

These objects are obtained with the method according to the inventionwhich method comprises optionally adding acidified retentate which issubsequently pasteurized to the retentate from the ultrafiltrated milk,acidifying the mixture with at least one starter culture to obtain apH-value of from 4.5 to 5.6, whereupon salt and optionally otheradditives are added in the desired concentration, and pumping theretentate, while supplying rennet, into cheese moulds or ready-madepackings, characterized in that the cheese is subjected to a finaltreatment in said cheese molds or ready-made packings under heattreatment at from 18° to 65° C. during a period of from 4 to 36 hours.

DETAILED DESCRIPTION OF THE INVENTION

I) In a preferred embodiment whole milk, skim milk or a similarnon-acidified milk product is ultra-filtrated with a concentrationfactor of from 2 to 6 times, and the retentate is collected in a numberof acidification tanks corresponding to the number of starter culturesused. To each tank one starter culture is added, which is selected fromamong low-flavor starter cultures, such as O-culture (C.H.O.-culture No.171, 173, etc.) and flavour-developing starter cultures, such asstreptococcus cremoris and rod bacteria, such as meso- and thermophilictypes, e.g. Lactobacillus helveticus og L. bulgaricus. When theacidification is completed after from 4 to 25 hours, preferably 6 to 12hours, at a temperature of from 18° to 46° C., preferably from 18° to22° C. for mesophilic bacteria and from 35° to 42° C. for thermophilicbacteria, a pH-value in the individual acidification tank of from 3.8 to5.0 is obtained. At high temperatures low pH-values are obtained. Thecontents of the individual acidification tanks are mixed to form adesired final pH-value of from 4.5 to 5.6, preferably of from 4.6 to4.8, most preferably 4.8, whereupon the desired salt concentration offrom 0.8 to 8%, preferably 1.5 to 6%, is adjusted preferably by additionof finely ground sodium chloride crystals. Where a portion of the saltis constituted by large crystals it is possible to obtain a small-holecheese as a cavity in the cheese is formed by the dissolution of thelarge crystals. With the addition of salt the acidified cheese milk ispreserved, and further growth of the bacteria is discontinued. Whilesupplying rennet, preferably a microbial rennet enzyme, the acidifiedcheese milk is then pumped into cheese moulds or preferably ready-madepackings which are sealed hermetically. The packing units are preferablytins made from plastics or cartons containing from 0.1 to 5 liters,preferably from 0.25 to 0.5 liters. The units are subsequently subjectedto a controlled heat treatment at a temperature of from about 18° C. toabout 65° C., preferably from 35° C. to 65° C., preferably in the formof hot-air circulation, however, alternative forms of controlled heattreatment may be applied, such as immersion into a water bath. The heattreatment effects renneting and coagulation as well as a conditioning ofthe cheese so that a firmer texture is obtained at higher temperatures.The temperature used depends on the rennet enzyme used. Conventionalcalf stomach rennet does not tolerate temperatures above 42° C. beforethey are inactivated whereas the preferred enzyme from Mucor sp.tolerates temperatures of up to about 65° C. The heat treatment lastsfrom about 4 hours to about 36 hours, preferably from 6 hours to 24hours. The duration depends i.a. on the volume of the packing units, aslarge volumes require more time. The heat treatment is decisive, i.a.for the final cheese texture and flavor.

II) According to a preferred embodiment of the invention an acidifiedretentate (pH=3.2 to 5.0, preferably 4.5) is produced fromnon-pasteurized ultra-filtrated milk wherein the acidification is basedon bacteria derived from purchased cheese or whey from the previousday's cheese production, or the acidification is effected asself-acidification with the bacteria flora of the non-pasteurized milkproper, end rennet enzyme is optionally added to provide a strongercasein cleaving. Moreover it is preferred to carry out lightpreservation of the acidified retentate by adding about 2% of salt. Theacidified ripened retentate is pasteurized and pasteurized non-acidifiedretentate (pH-value=about 6.6) is added in a 1:3 w:w ratio or in a ratiowhich ensures a pH-value=about 6.1 of the mixed retentate. At a pH-valueof<about 6 there is a risk of bacteria encapsulation and incompletepasteurization. The mixed retentate is pasteurized and then acidified asdescribed above under I). Salt is subsequently added and the cheese milkis pumped into cheese molds or ready-made packages as described aboveunder simultaneous addition of rennet. This embodiment makes it possibleto accelerate the ripening of cheese with an inherent taste from lacticacid bacteria which are characteristic for a particular region, e.g.Tabriz, Curdistan, Egypt and Turkey, as the bacteria must act for asufficiently long time in the acidifying retentate prior topasteurization to form enzymes which in continued fermentation imparts acharacteristic taste to the cheese. Depending on the pH-value obtainedin the acidification, the acidified pasteurized retentate is added tothe non-acidified retentate and preferably co-pasteurized therewith in ascraped surface heat exchanger or in a melting pot to inactivate thelactic acid bacteria. Cheese of the feta and domyati types or creamcheese is primarily produced which immediately obtains the desiredripening and taste.

III) According to a further preferred embodiment soft ripened cheese isproduced as described above under I) and which may be acidified bydifferent pure cultures. Following completed, heat treatment and whenthe desired ripening depth is present, indicating finished flavordevelopment, the ripened cheese is stirred into fresh or thoroughlyacidified retentate in an amount of from 5 to 25%, preferably 15%,whereby the gel forming ability of the casein is maintained. By stirringup to about 95% of retentate into ripened cheese a considerable volumeincrease of the ripened cheese is obtained without loss of taste andaccelerated distribution of the cheese with inherent taste and ripeningdepth is achieved, and also e.g. cow-milk cheese acquires new tastecharacteristics when retentate from milk from other animal species isadded.

IV) According to a further preferred embodiment a retentate is producedas described under I) above wherein from 3 to 9%, preferably about 5%,of a taste concentrate is added following acidification and whereuponthe remaining cheese production proceeds as described under I).

The taste concentrate is produced from the permeate from ultra-filtratedmilk wherein additional fat, such as milk fat, preferably in aconcentration of from 0 to 10% and protein, preferably milk protein,e.g. casein, preferably in a concentration of from 1 to 15%, is added.The permeate thus enriched is inoculated with at least one bacteriaculture in a number of tanks corresponding to the number of bacteriacultures and is allowed to ferment (ripen) at optimum temperature. Theacid formed in the bacteria fermentation is neutralized in a mannerknown per se, preferably by addition of a base, such as sodium hydroxideor ammonia, so as not to impair the bacteria growth by a low pH-value,and accumulation of bacteria bio mass is effected. The fermentedpermeate is purified of bacteria, preferably by filtering off thebiomass and it is filled into closed containers wherein the enzymaticactivity released in the fermentation is maintained.

Retentate acidified according to the method described herein is added tothe permeate thus enzyme-enriched following inactivation of the bacteriaculture(s) used in the acidification of the retentate by salting wherebythe ripening of the cheese is accelerated considerably and whereby it ismade possible to provide considerable taste control as theenzyme-enriched permeate having different taste qualities may be storedand added to the acidified retentate according to wish. Alternativelythe salting of the acidified retentate may be effected by means of asalt content in the fermented permeate. Cheeses produced with theaddition of the taste concentrate described above are preferably firmsliceable cheese types which, accordingly, may be produced with inherenttaste and/or ripening.

In the method according to the invention a wide range of cheeses, suchas cream cheeses and fresh cheese spreads and soft, semi-firm and firmtypes made from milk from cows, mares, goats and sheep may be produced.No salt diffusion takes place in the cheeses, as the salt concentrationis adjusted prior to the addition of rennet and the coagulation.

Milk, as used herein, includes all kinds of milk, such as whole milk,low-fat milk, skimmilk, buttermilk, etc., which may be pasteurized,sterilized, homogenized or in any other way methoded and wherein themilk components are optionally adjusted.

Furthermore preservatives are dispensable in case of direct pumping ofacidified, salted rennet-added retentate into ready-made packings.

The taste variation and final pH-level in the cheeses are preferablyobtained in the package by release of enzymes from the starter culturesin the heat treatment and in an optional subsequent storage ripening atambient temperature.

In the production of cream cheese it may be necessary to add meltingsalts, such as citrates or phosphates, which may be carried outconcurrently with the salt addition.

The method also permits the production of a very large number of cheesetypes in the same production plant by combining retentates acidifiedwith different starter cultures. The cheese types may further bedifferentiated by the choice of heat treatment of the cheese in the salepackage in its sealed state. Finally the production time is reducedsubstantially as ready-for-sale cheeses may be produced in from 7 to 14days. The simultaneous salt- and rennet-addition relieves the work loadconsiderably.

Where acidified retentate is pumped into cheese molds under simultaneoussupply of rennet, the cheese moulds should be tight containers as thecoagulation is not yet completed. Renneting and coagulation is effectedin the cheese molds under separation of serum and following a suitableheat treatment as described above and the cheeses are taken out anddried and further processed in a manner known per se. Firm cheeses witha high content of dry matter, i.e. ≧50% of dry matter, will receivesurface treatment. Such cheeses may optionally be produced by mixingnon-acidified retentate with the acidified retentate in connection withthe rennet addition.

The invention also relates to cheese produced by the method and inparticular the cheese types described in the following examples.

EXAMPLE 1 The production of domyati (Egyptian feta type)

Pasteurized, homogenized or non-homogenized whole milk (2000 kg) withstandardized fat content is subjected to ultrafiltration (Alfa Laval ABROMICON System, 50° C.) to obtain 38% of retentate dry matter. The fatcontent of the retentate dry matter thereby becomes 40%. The retentateis pasteurized at 76° C., transferred to an acidification tank andadmixed with 2% of a flavor-poor starter (C.H.O.-culture No. 171 fromChr. Hansens Laboratorium). The acidification is effected at 26° C. for18 hours and a final pH-value of 4.8 is obtained. Finely ground sodiumchloride is subsequently added to obtain a salt content of 3.5%. Undersimultaneous supply of cheese rennet, 20 g of 2% aqueous solution per kgof acidified retentate, the still fluid cheese curd is dosed into 500 grpackings which are closed immediately. A Mucor sp. rennet "Rennilase"from Novo Nordisk A/S is used. The packing units are then heat treatedat 42° C. for 18 hours, and the units are stored at ambient temperature.

EXAMPLE 2 Production of Feta cheese

The production is effected as in example 1 except that the heattreatment is carried out at 50° C. for 10 hours.

EXAMPLE 3 Production of cream cheese

The production is effected as in example 1 except that the rennet enzymeis chymosine and that simultaneously with the sodium chloride additionmelting salt is added in the form of citrate to obtain a melting saltcontent of 0.2% of the crude cheese weight. The treatment is carried outat 50° C. for 6 hours.

EXAMPLE 4 Production of firm sliceable cheese

The production is effected as in example 1 except that half of theretentate is not acidified but pasteurized and evaporated at 76° C. in ascraped surface heat exchanger with vacuum chamber (Alfa-Laval CONVAP)to obtain a dry matter content of 66% and is admixed with the acidifiedretentate/cheese curd (dry matter content of 44%) to which 3% of sodiumchloride has been added. The total dry matter content is 55%. The heattreatment is carried out at 45° C. for 4.5 hours.

EXAMPLE 5 Production of domyati with inherent ripening depth

Crude cheese curd is produced in a closed container in an amount of from0.5-25 kg, preferably in the milk-rich season, like in example 1 withdifferentiated dry matter and fat percentage to compensate for seasonalfluctuations.

The curd is taken out after 3 months and added to new production with amaximum of 25%, the cheese curd being, following stirring, passed to amixer pipe where it is admixed with 75% of new acidified retentate andsupply of rennilase (2% aqueous solution) and is dosed into ready-madepackages.

The mixing ratio and standardization is balanced so that the finishedproduct has the desired composition following which the curd is heattreated like in example 1.

EXAMPLE 6 Production of Feta cheese with inherent ripening depth

As in example 5 except, however, that heat treatment is carried out asin example 2.

We claim:
 1. A method of producing cheese from ultrafiltration-concentrated milk comprising acidifying a starting retentate from the ultrafiltrated milk with at least one starter culture to obtain a fermented retentate with a pH value of from 4.5 to 5.6, adding an effective amount of salt, pumping the fermented retentate, while supplying rennet, into cheese molds or ready-made packages to obtain a curd, and heat treating the curd in said cheese molds or ready-made packages at from 18° to 65° C. for a period of from 4 to 36 hours.
 2. The method according to claim 1, further comprising adding together with the salt, an effective amount of at least one additive to the fermented retentate.
 3. The method according to claim 1, wherein, following acidification, said method further comprises adding a taste concentrate, said taste concentrate comprising a permeate obtained from the ultrafiltrated milk, wherein protein and optionally fat components are added to enrich the permeate, and which is inoculated with at least one bacteria culture and fermented under simultaneous neutralization of the acid formed and subsequently purified of bacteria.
 4. The method according to claim 3, wherein the taste concentrate is added in an amount of from 3 to 9% by weight of the fermented retentate.
 5. The cheese produced by the process of claim
 1. 6. A method of producing cheese from ultrafiltration-concentrated milk comprising adding an acidified and subsequently pasteurized processed retentate to a starting retentate from the ultrafiltrated milk to form a mixture, acidifying the mixture with at least one starter culture to obtain a fermented mixture with a pH value of from 4.5 to 5.6, adding an effective amount of salt, pumping the fermented mixture, while supplying rennet, into cheese molds or ready-made packages to obtain a curd, and heat treating the curd in said cheese molds or ready-made packages at from 18° to 65° C. for a period of from 4 to 36 hours.
 7. The method according to claim 6 further comprising adding, together with the salt, an effective amount of at least one additive to the fermented retentate.
 8. The method according to claim 6, comprising acidifying the processed retentate with impure bacteria cultures having a known taste character.
 9. The method according to claim 6, comprising adding the processed retentate having a pH-value of from 3.2 to 5.0 to obtain a pH value of above 6 in the mixture and pasteurizing the mixture prior to acidification.
 10. The method according to claim 6, wherein, following acidification, said method further comprises adding a taste concentrate, said taste concentrate comprising a permeate from the ultrafiltrated milk, wherein protein and optionally fat components are added to enrich the permeate, and which is inoculated with at least one bacteria culture and fermented under simultaneous neutralization of the acid formed and subsequently purified of bacteria.
 11. The method according to claim 10, wherein the taste concentrate is added in an amount of from 3 to 9% by weight of the fermented retentate.
 12. The method according to claim 6, wherein the processed retentate is added in an amount of from 5% to 25% by weight of the mixture.
 13. The method according to claim 6, wherein the processed retentate is ripened cheese which has been pasteurized.
 14. The cheese produced by the process of claim
 6. 15. A method of producing cheese from ultrafiltration-concentrated milk comprising acidifying a starting retentate from the ultrafiltrated milk with at least one starter culture to obtain a fermented retentate with a pH value of from 4.5 to 5.6, adding an acidified and subsequently pasteurized processed retentate to the fermented retentate to obtain a mixture, adding an effective amount of salt, pumping the mixture, while supplying rennet, into cheese molds or ready-made packages, and heat treating the mixture in said cheese molds or ready-made packages at from 18° to 65° C. for a period of from 4 to 36 hours.
 16. The method according to claim 15, further comprising adding together with the salt, an effective amount of at least one additive to the fermented retentate.
 17. The method according to claim 15, comprising acidifying the processed retentate with impure bacteria cultures having a known taste character.
 18. The method according to claim 15, wherein, following acidification, said method further comprises adding a taste concentrate, said taste concentrate comprising a permeate from the ultrafiltrated milk, wherein protein and optionally fat components are added to enrich the permeate, and which is inoculated with at least one bacteria culture and fermented under simultaneous neutralization of the acid formed and subsequently purified of bacteria.
 19. The method according to claim 18, wherein the taste concentrate is added in an amount of from 3 to 9% by weight of the fermented retentate.
 20. The method according to claim 15, wherein the processed retentate is added in an amount of from 5% to 25% by weight of the mixture.
 21. The method according to claim 15, wherein the processed retentate is ripened cheese which has been pasteurized.
 22. The cheese produced by the process of claim
 15. 